The present invention relates generally to bicycle wheels, and particularly to a system for locking a tire bead into engagement with a bicycle rim.
Pneumatic bicycle wheels commonly include a hub, spokes extending radially from the hub, a rim secured to the outer ends of the spokes, and a tire mounted on the rim. While many bicycle wheels include an inner tube between the tire and rim for holding pressurized air, some bicycle rims eliminate the inner tube and instead create a sealed chamber between the tire and the rim. In order to create such a “tubeless” wheel, it is important to have an airtight seal between the tire bead and the sidewalls of the rim. In tubeless wheels, the internal air pressure presses and holds the tire bead in engagement with the rim.
In order to create a proper seal in a tubeless wheel, a precise fit is desired between the tire bead and the rim. Some rims use a small lip to keep the tire in place. The standard fit between a tubeless tire and a rim works well under easy riding with medium to high tire pressures. This system, however, will not work well under extreme cornering loads or when tire pressures are low. High cornering loads can cause the tire bead to stretch and lift off of the rim's bead seat and cause air to escape, or completely jump off the rim in extreme conditions. Low tire pressures are often desirable on bicycles for maximum traction and smoother riding experiences. However, such low-pressure tires have been known to lose pressure when the tire bead separates from the rim because there is insufficient air pressure holding the tire bead in place.